Safety devices of the above-described type of this class are used, e.g., where tree care work, such as the securing of the crown or pruning and other work must be performed directly in the trees. Another intended use is in all work at elevated locations, e.g., on facades or roofs or in mountain-climbing technique for securing one's own person and other persons. It is necessary in the above-described operations to protect the climbing person from falling by a corresponding safety device at the moment at which he loses his grip within a tree crown or on a mountain face. For example, catching devices, which run together with the person, are pushed over a holding rope, and from which a separate fastening is established to the climber, have been known for this purpose. As soon as the climber loses his grip and the connection between the climber and the catching device is tensioned as a result, the holding rope running through the catching device is clamped, so that the climber is prevented from falling. Such catching devices have proved, in principle, to be successful, but no dynamic upward and downward movements are possible under load, especially with the double rope.
Moreover, lowering devices with automatic stop function have been known from the state of the art. The securing rope now runs through the device and is automatically clamped. A pressure on a release level present at the lowering device causes the lowering device to release the securing rope running through, so that the climber can displace the lowering device on the securing rope. This securing means has the drawback that the second hand of the climber must secure the rope end running through, while the first hand actuates the release lever. In addition, the ascending of the climber by means of the rope is not possible when such devices are used on the double rope.
Furthermore, so-called height-securing devices have been known in the state of the art, which are arranged between a suspension point and the climber. The height-securing device blocks automatically in the case of an abrupt load of the securing rope, which occurs in the case of a fall. In addition, such a device may be equipped with an automatic rope return function via a spring mechanism. Such devices are used exclusively for securing against falling; they have the drawback that adjustable lowering is not possible under load on the rope. Therefore, they are unsuitable especially for working in tree crowns or the like.
Besides the lowering and catching devices described in the introduction, there also are lowering and rescue devices that are arranged at fixed attachment points. Such devices make possible the uniform, automatic lowering of persons with a corresponding stop function. In addition, they may be provided with hand cranks, which make it possible to pull up persons in rescue situations. Such devices are relatively heavy due to their design and therefore they cannot be carried directly by the climber. Moreover, dynamic ascending by means of the rope is not possible with these devices, because they cannot be used according to the double rope technique due to their suspension.
It is common to all the above-described devices that they are designed for special fields of application and they lack the possibility of performing dynamic ascending processes by means of the rope. In addition, the safety function of such devices does not usually include a fall-dampening function; on the contrary, the safety function begins immediately upon load.